In the field of toners for electrophotography, with the progress of electrophotographic systems, it has been demanded to develop toners adaptable for high image quality and high copying speed. From the viewpoint of the high image quality, the toners have been required to have a small particle size. Thus, there has been reported a so-called chemical toner obtained by a chemical method such as a polymerization method and an emulsification and dispersion method in place of the conventional melt-kneading method. Further, from the viewpoint of the high copying speed, there has been proposed a toner to which a releasing agent is added as an internal additive in order to improve a low-temperature fusing property thereof.
For example, Patent Literature 1 aims at providing a toner for electrophotography which is excellent in low-temperature fusing property and anti-high-temperature offset property by preventing liberation of releasing agent particles from toner particles upon production of the toner, and discloses a process for producing a dispersion of a releasing agent for toners containing releasing agent particles which includes a step of mixing a dispersion of a releasing agent containing a carboxyl group and having an acid value of from 0.5 to 20 mgKOH/g and an oxazoline group-containing polymer. Also, Patent Literature 2 aims at providing a toner for electrophotography which is excellent in heat-resistant storage stability and has a wide fusing temperature range, and discloses a process for producing the toner for electrophotography which includes steps of melting and kneading a toner raw material containing a resin binder containing a polyester and a releasing agent, and emulsifying the resulting melted and kneaded product in an aqueous medium, followed by an aggregating step or a fusing step in which an oxazoline group-containing polymer is added to the resulting emulsion.
Patent Literature 1: JP 2009-133946A
Patent Literature 2: JP 2009-192699A